1. Field of the Invention
The present invention relates to a system including a location server and a target terminal which provides a triggered location service. More particularly, the present invention relates to a method for providing a location value of the target terminal in a location information providing system.
2. Description of the Related Art
A triggered location service refers to a service for calculating a location value of a target terminal in every specific period or occurring specific criteria and providing a location service agent with the location value. At this time, in order to calculate the location value, a location server and the target terminal exchange a message for the positioning. In this case, one of the location server or the target terminal should transmit the message for starting a connection for the positioning to the other.
FIG. 1 is a flowchart illustrating an operating procedure of calculating a location value of the target terminal according to a conventional method for providing the location service.
Referring to FIG. 1, the operating procedure of calculating the location value of the target terminal according to the conventional method for providing location information is as follows. Hereinafter, the target terminal and the location server will be described on an assumption that they use a Secure User Plane Location (SUPL) protocol.
A. An SUPL AGENT transmits a Mobile Location Protocol Triggered Location Request Report (MLP TLRR) to a Home SUPL Location Platform (H-SLP). The H-SLP examines a triggered location service authority of the SUPL AGENT by using a CLIENT ID and a SUBSCRIBER PRIVACY of the target terminal by using a Mobile Subscriber Identity (MSID).
B. The H-SLP determines if a Target Secure User Plane Location (SUPL) Enabled Terminal (SET)(Target SET) is in a roaming state, and if the Target SET performs the positioning by using the SUPL protocol.
C. The H-SLP transmits a location service initiating message (SUPL INIT message) to the Target SET and starts the triggered location service. At this time, the SUPL INIT message may be sent in a form of a Wireless Application Protocol push (WAP push) or a Short Message Service (SMS) TRIGGER method. And the SUPL INIT message includes parameters such as a SESSION ID indicating a connection between the H-SLP and the Target SET, a TRIGGER-TYPE indicating a kind of the triggered location service, a POS METHOD indicating the positioning method and an SLP mode indicating a form of the H-SLP.
D. If the Target SET receives the SUPL INIT message, it is connected to a data network.
E. The Target SET transmits an SUPL TRIGGERED START message. At this time, the SUPL TRIGGERED START message includes parameters such as the SESSION ID, a Location ID (LID) indicating a location of a network in which the Target SET currently exists, a SET-CAPABILITY indicating the positioning method of the Target SET or the like.
F. The H-SLP transmits the SUPL TRIGGERED START message, determines the positioning method, and transmits criteria for the triggered location service to the Target SET.
G. The H-SLP transmits the MLP Triggered Location Reporting answer (TLRA) message to the SUPL AGENT and reports the start of the requested triggered location service.
H. The Target SET memorizes a period for the positioning and transmits an SUPL Positioning Initiating message (SUPL POS INIT message) for starting the positioning. At this time, the message includes the LID as information on the network in which the Target SET exists.
I. The H-SLP and the Target SET perform the positioning.
J. The H-SLP transmits a location value resulting from the positioning to the SUPL AGENT.
Among those steps, steps H, I and J are repeated during the triggered location service. Accordingly, in the conventional method, the Target SET transmits the message indicating the start of the positioning during the triggered location service to the H-SLP. That is, the Target SET memorizes a period for performing the positioning periodically, and when the period arrives, the Target SET transmits the message for starting the positioning to the H-SLP. And then, if the H-SLP receives the message for starting the positioning session from the Target SET, the positioning procedures is started.
That is, the only Target SET, not the H-SLP checks the period for the positioning. Therefore, the H-SLP waits for the SUPL POS INIT message transmitted from the Target SET, and then starts the positioning after receiving the message. Thus, there is a problem in the conventional method in that if the Target SET misses the period for performing the positioning and fails to transmit the SUPL POS INIT message to the H-SLP, the positioning cannot be started. In such, the location value is not calculated in the corresponding period so that the location service cannot be performed. This corresponds to not only the triggered location service but also a deferred event occurrence service. That is because that the location value is calculated according to a specific period so as to provide the deferred event occurrence service, and the occurrence of the corresponding criteria is determined by using the location value, so that the deferred event occurrence service is in progress.
Accordingly, when the Target SET misses the positioning period due to a turn-on after the power turns off or the predetermined period due to a timer error of the Target SET, the Target SET fails to transmit the SUPL POS INIT message to the H-SLP. Further, in this case, it does not start the positioning so that the location value of the Target SET is not calculated. Therefore, there arises a problem in that an appropriate triggered location service is not provided.